Railway track circuit for track sections, including non-insulated portions of track



y 22, 1956 R. R. MCGUIRE 2,747,080

RAILWAY TRACK CIRCUIT FOR TRACK SECTIONS, INCLUDING NON-INSULATED PORTION OF TRACK Filed Nov. 22, 1950 IN V EN TOR.

7M 12. ffl'une BY 2 H15 ATTORNEY RAILWAY TRACK CIRCUIT FOR TRACK SEC- TIONS, INCLUDING NON-INSULATED POR- TIONS OF TRACK Richard R. McGuire, East Cleveland, Ohio, assignor to Westinghouse Air Brake Company, a corporation of Pennsylvania Application November 22, 1950, Serial No. 197,057

3 Claims. (Cl. 246-41) My invention relates to railway track circuits, and particularly to an improved railway track circuit for providing continuous control of railway signals by a train on a stretch of track which includes a section in which the two parallel rails of the track cannot be transversely insulated one from the other, as is usually provided by the cross ties and spacing of the rails. One example of such a situation is that found at the intersection of two railways at grade. In order to provide sufiicient rigidity and strength, the crossing frog assembly is usually constructed in such manner as to render the insulation of one running rail from the other very difficult.

It has heretofore been proposed to insulate such a section completely from the track on either side of the crossing and to provide track circuits on either side of the crossing, which track circuits may comprise two individual track circuits with separate track batteries and relays, or may comprise a track section on one side of the crossing connected to a track battery and a section on the other side of the crossing connected to a track relay, together with jumper wires to carry the track circuit energy around the dead section.

If, however, the length of the dead section is longer than the wheel base dimensions of the shortest locomotive or other vehicle which moves over the crossing, such as, for example, where one railway intersects another railway having relatively closely spaced multiple tracks, it is possible for a short vehicle to occupy the dead section without shunting the adjacent track circuits. Where such track circuits enter into the control of signals governing train movements over the crossing, it is thus possible that a signal might falsely indicate that the crossing was clear when it would actually be occupied by a car or a locomotive.

To prevent such a possibility, it has heretofore been proposed to provide special arrangements of circuits known in the art as trap circuits to insure that a train or vehicle, which commences a movement over the crossing, must complete the movement before the signals can be cleared for another train movement over the crossing. These arrangements are subject to failure, however, in the case where the last car of the train becomes disconnected and remains in the dead section while the remainder of the train continues its movement away from the crossing.

Accordingly, it is an object of my invention to provide an improved railway track circuit arranged to energize certain portions of a plurality of track structures, insulated one from the other, so that the energy is efiectively shunted by the metal structure 'of a car spanning one or more of the track structures.

Another object of my invention is to provide an improved railway track circuit arranged to energize the track structure of a plurality of track crossings with-track circuit energy in such manner that adjacent crossing structures are energized with opposite polarities, so that a car nited States Patent ice spanning two of the crossings will shunt the track circuit energy through the metallic structure of the car.

A further object of my invention is to provide an improved railway track circuit arranged to provide supplemental shunting of the track circuit energy through the frame of a car occupying the track circuit in the portion or portions of the track circuit in which the usual wheelto-wheel shunting is ineffective.

Other objects of my invention and features of novelty thereof will be apparent from the following description, taken in connection with the accompanying drawing.

In practicing my invention, I provide suitable connections to connect two or more adjacent dead sections of track to a conventional track circuit adjacent the dead sections, in such manner that the dead sections are energized by the track circuit energy of the adjacent track circuits, and so that adjacent dead sections are energized with energy of opposite polarity. Accordingly, when a vehicle spans two of the dead sections, the track circuit energy of the adjacent track circuits is shunted, to release the associated track relay.

I shall describe one form of an improved railway track circuit embodying my invention, and shall then point out the novel features thereof in claims.

The single accompanying drawing is a diagrammatic view of a section of single track railway intersected by a double track railway at grade, in which the single track stretch is provided with a track circuit embodying my invention.

Similar reference characters refer to similar parts in the drawing.

Referring to the drawing, there is shown a stretch of single track railway having track rails 1 and 2, intersected by two other railways at the grade crossings A and B. The construction of the crossing frogs at crossings A and B are assumed to be such that the rails 1 and 2 of the single track stretch are solidly connected, preventing the use of a conventional track circuit through the crossings.

The single track is divided into several sections by insulated joints 3 in at least one of the section rails, forming a section a-b adjoining the crossing A and a section de adjoining the crossing B. The two crossings A and B are insulated from each other by insulated joints 3 in both rails 1 and 2 at location c between the crossing. Thus, at the crossings the track is formed with two adjacent sections insulated from each other, a section bc including the crossing A and a section cd including the crossing B. Additionally, insulated joints are installed on each of the crossing tracks at A and B to confine the energy in these crossings to the immediate vicinity of the crossing.

A track battery TB is connected across the rails 1 and 2 at point e, and a track relay is connected across the rails 1 and 2 at point a. Although herein shown and described as employing direct current track circuit energy, it will be obvious that other types of track circuits will operate equally as well when arranged in accordance with my invention, such as, for example, alternating current track circuits, or coded energy track circuits.

Two signals, designated by the reference characters 15 and 28 are located at points a and 2, respectively, to govern train movements on the single track railway over the crossings A and B.

The signals 18 and 28 are shown as being of the conventional color-light type, each having a green lamp G, which when lighted indicates proceed, and a red lamp R, which when lighted indicates stop. the signals 18 and 28 are supplied with energy from a suitable source of energy, such as the battery LB, by a circuit including a contact a of track relay TR, so that when relay TR is energized and its contact a is picked up,

The lamps of the green lamps G of the signals are lighted, and when relay TR is deenergized and its contact a is released, the red lamps R of the signals are lighted. These lighting circuits are readily understandable from the drawing and a detailed description of them is deemed unnecessary.

A jumper wire 7 is conected between rail 1 at the left of the insulated joint 3 at location b and, rail 1 at the right of the insulated joint 3 at location 0. Another jumper wire 9 is connected between rail 2 at the left of the insulated joint 3 at location and rail 2 at the right of the insulated joint 3 at location 1!.

In the normal condition, as shown in the drawing, Current flows from the positive terminal of battery TB through section rail 1 from point e to. point 0, through jumper 7 to point 5, through rail 1 from point b, to point a, through the winding of the track relay TR, through rail 2 to point c, through the jumper wire 9 to point d, and through rail 2 to point e and the negative terminal of battery TB. Conventional polarity marks are shown at various points on the drawing to more clearly designate the polarities existing at the various points. It will be seen that the crossing structures A and B comprising the usual frogs and guard rails, not shown in detail in order to clarify the drawing, are energized with dilierent polarities. That is, all the metallic structure associated with crossing A has a negative polarity with respect to the metallic structure of the adjacent crossing B. As previously pointed out, the insulated joints in the two crossing tracks at A and B, installed as close as practicable to the crossing itself, confine the energization of the crossing tracks to the immediate vicinity of the crossing.

From the foregoing, it will be apparent that with no train occuping the single track between points a and e, the track relay TR will be energized by current supplied from the track battery TB. Accordingly, both signals 18 and 23 will have their green lamps lighted to indicate that the crossing is clear.

It will now be assumed that a train, moving from left to right, and having a greater length than the section bd passes signal and moves over the crossing. The wheels and axles of the train shunt the energy supplied to the track relay as long as any portion of the train is in the section ab, or the section d-e. Accordingly, the track relay will be continuously shunted while any portion of the train is between the signals 15 and 23, the contact a of the track relay will be released, and the red lamps R of the signals will be lighted, to indicate that the stretch including the crossings A and B is occupied.

When the train moves entirely out of the section a-e, energy will again be supplied to the winding of the track relay, and its contact a will pick up, to light the green lamps G of the signals, so that the apparatus is restored to its normal condition, as previously described.

It will now be assumed that a train or vehicle shorter in length than the section bzl moves into or stands upon this section. The track circuit energy will be shunted by current flowing from B crossing section (cd), which is energized with a positive polarity, through the wheels and trucks of the train or vehicle which are standing upon this section, through the metallic underfrarnes and/or the metallic bodies of the train or vehicle, and through the trucks and wheels which are standing upon the A crossing section (II-C), and which are energized with a negative polarity. Accordingly, the track relay TR will be released and the red lamps R of signals 15 and 25 will be lighted to indicate that the crossing is occupied. While the vehicle or short train occupies sections a-b or d -e, the track relay TR will be shunted in the usual manner, that is, wheel-to-wheel. When the vehicle or short train moves out of the section a-e, they supply of energy to track relay TR is resumed, and its contact a picks up to cause the signals 18 and 25 to display their green aspect. The system is now restored to its normal condition, as. originally described.

It will be apparent that the arrangement embodying my invention is not limited to a double track crossing as shown, but may be employed where any number of tracks cross a single track, by arranging the insulated joints and the jumper wires to energize adjacent crossing tracks with energy of opposite polarity.

It is to be noted that the track circuit arrangement provided by my invention may be employed with so-called trap circuits usually employed. at such locations, to further increase the safety provided by such trap circuits. For example, my arrangement may be employed with the trap circuit system shown and described in Letters Patent of the United States No. 2,039,820, granted May 5, 1936. to Ronald A. McCann et al., in which the track relay R2 could be governed by a track circuit arranged in accordance with my invention.

Although I have herein shown and described only one form of improved railway track circuits embodying my invention, it is to be understood that various changes and modifications may be made therein within the scope of: the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. In combination, a first and a second section of railway traclt, adjacent and insulated one from the other, a source of electrical energy having two terminals of op posite relative polarity, a relay having a winding with a first and a second terminal and having at least one contact which is picked up or released according as energy is supplied or is not supplied to the winding of the relay, means for connecting one of said source terminals to each of the rails of said first track section, means for connecting the other of said source terminals to each of the rails of said second track section, and means for connecting one terminal of the winding of the relay to the rails of said first track section and for connecting the other terminal of the winding to said second track section, whereby the relay will be shunted and its contacts released when said first and said second sections are connected through the metallic parts of a vehicle occupying said first and said second sections.

2. In combination, a plurality of adjacent track sections each having its parallel running rails electrically con nected, each of said sections, being insulated from the adjacent sections, a source of electrical energy, means for energizing said sections from said source so that adjacent sections have opposite relative polarities, and relay means connected to said source through said sections, whereby said relay means is shunted when adjacent sections are metallically connected by a car occupying said adjacent sections.

3. In combination, a plurality of adjacent track sections having each track rail nietallically connected to the other track rails in said section, each of said sections being insulated from the adjacent sections, a source of electrical energy having a pair of terminals, a relay having contacts which are picked up or released according as energy is or is not supplied to the terminals of. a winding of the relay, means for connecting alternate ones of said track sections to one terminal of said source and to one terminal of said relay winding, and means for connecting the other ones of said sections to the other terminal of said source and the other terminal of said relay, whereby the relay is shunted when adjacent sections are metallically connected by a car occupying said adjacent sections.

Reierences. Cited in the file of this patent UNITED STATES PATENTS 2,111,501 Wight Mar. 15, 1938 2,111,513 Phinney Mar. 15, 1938 2,289,857 Allen July 14, 1942 2,366,802 Pilasterer Jan. 9, 1945 2,591,035 Young Apr. 1, 1952 

